1. Field of the Invention
This invention is in the field of waterbed mattresses, particularly mattresses made up of a plurality of individual cells, with no fluid communication between cells.
This invention is related to my co-pending application number 06/896,770 filed Aug. 14, 1986, entitled "WATERBED HEATER".
2. Description of the Prior Art
Numerous changes have been made in the construction of the waterbed mattress since the waterbed was first introduced in the 1960's. The original waterbed mattresses consisted of a single, large, flexible bladder which would be filled with water or other liquid and supported in a sturdy support frame. A sheet of waterproof liner material would be placed between the mattress and the frame in order to protect the frame and the adjacent area from water damage in the event of mattress leakage. These mattresses gained widespread popularity with college students, but were not immediately accepted by the general public because the bladders were subject to wave motions and continuing oscillating responses to relatively small motions, which most people found disturbing and uncomfortable. In addition, the mattresses when filled often weighed upwards of 500 lbs. which made them impossible to move from one room of a house to another. Still another problem was that when leakage occured it would be necessary to empty the mattress completely, patch the mattress and then refill it. In addition, the amount of water involved in such a leak could result in substantial water damage to the surroundings, and would be extremely difficult to clean up. Furthermore, the total weight of the frame, bladder and water often exceeded the permissible floor loading in residential structures, which resulted in the practice of prohibiting waterbeds in many apartments.
In response to consumer fears and complaints about the excessive wave motions and oscillations of conventional waterbed mattresses, numerous mattresses have been developed which incorporate complicated baffle structures or other motion damping systems for reducing wave action. Exemplary mattresses with dampening constructions are disclosed in U.S. Pat. No. 4,168,555 to Benjamin, U.S. Pat. No. 4,204,289 to Fogel, U.S. Pat. No. 4,296,510 to Phillips, U.S. Pat. No. 4,310,936 to Benjamin, U.S. Pat. No. 4,517,691 to Philips, U.S. Pat. No. 4,577,356 to Johenning et al, U.S. Pat. No. 4,430,764 to Finkelstein, and U.S. Pat. No. 4,475,257 to Phillips. These reduced-motion mattresses have more of the look and feel of conventional inner spring or foam bed mattresses, yet retain the more even weight distribution and the beneficial "floating" feeling for which the earlier waterbed mattresses were praised. As a result, the popularity of waterbeds has increased tremendously in recent years, resulting in their acceptance among all segments of the population.
However, although the complicated baffle constructions disclosed in the aforementioned patents solve the problem of excessive wave motion in the mattress, they do nothing to alleviate the problems of weight and leakage. In fact, the baffles tend to increase the weight of the waterbed mattress, as well as add to the cost and complexity of manufacturing.
One mattress which has been designed in an attempt to solve the weight and leakage problems, as well as the problem of wave motion, is disclosed in U.S. Pat. No. 4,221,013 to Echevarria. The Echevarria mattress comprises a plurality of individual tubes supported in a cavity defined by pairs of foam panel members, with conventional liner material placed below the tubes to protect the bed frame and adjacent areas. The individual tubes do not transmit significant side forces or wave motion to the other tubes, and thus provide a steadier sleeping surface than the conventional single-bladder mattress. In addition, the individual tubes can be removed from the bed for relatively easy filling and draining. Also when leakage occurs, it is necessary only to repair or replace a single leaky tube rather than to remove an entire bulky bladder for patching. Nevertheless, the mattress of Echevarria suffers from several drawbacks. First of all, although the tubes do not transmit side forces to one another, waves are still free to travel longitudinally from one end of a tube to the other end. Thus, some oscillating motion is still felt. In addition, the individual tubes are designed to hold approximately 50 lbs. of water. Although this obviously makes then easier to transport than the conventional bladders averaging 500 lbs., they are still heavier than desirable for the average consumer. Furthermore, the foam panel members, which are required on all sides of the mattress to prevent the tubes from rolling apart and to define a cavity for collecting water should a leak occur, increase the cost of the waterbed ensemble and are bothersome to store and transport when the waterbed is to be moved to a new location. Also, although the amount of water involved in a leak will be less than in a conventional bladder type mattress, the leak will still be difficult to clean up since the water will tend to spread out over the entire surface of the unitary liner. Still another problem of the aforementioned mattress is that, since there is no fluid communication between the individual tubes, heat transfer between tubes is poor. Thus, a conventional waterbed heating unit, consisting of a single heating pad placed under the center of the mattress, will not satisfactorily heat those tubes which are located farthest from the center.
Finally, in addition to their use by private consumers, waterbeds are increasingly being used by hospitals, especially in the treatment of burn victims, paraplegics, and other immobilized patients who are subject to bedsores. The uniform weight distribution afforded by water-filled mattresses eliminates regions of high pressure under a patient's body, thus preventing bedsores from forming. However, like the waterbeds designed for consumer use, the waterbeds designed for hospital use have been far too heavy to be practical. In addition, it is generally desirable for hospital beds to be adjustable so that the patient can elevate parts of his or her body relative to other parts. None of the prior art mattresses have been found suitable for use on adjustable beds, since the water tends to run "downhill" from the elevated to the level portion of the bed, resulting in uneven pressure distribution.
Thus, there exists a longfelt need in the art for a new and improved waterbed mattress with reduced wave motion, which is easy to transport and fill, minimizes leakage and which is suitable for use on adjustable beds.